Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Conventional lithium-ion and lithium polymer batteries are typically composed of a lithium cobalt oxide (LiCoO2) cathode, a graphite anode, a polymer separator, and a liquid electrolyte. One limitation of conventional lithium-ion and lithium polymer batteries is that the liquid electrolyte presents safety issues, as it may become flammable if a short occurs between the anode and cathode of such a battery due to, for example, a defect or mishandling. Another limitation of conventional lithium-ion and lithium polymer batteries is that, because such batteries have a high ratio of inactive (e.g., polymer separator, liquid electrolyte) to active materials (e.g., LiCoO2 cathode and graphite anode), they have a limited energy density of approximately 500-550 Wh/L.
Solid-state batteries present an improvement over conventional lithium-ion and lithium polymer batteries in both energy density and safety. Solid-state batteries are typically composed of a LiCoO2 cathode, a lithium anode, and a solid-state lithium phosphorous oxynitride (LiPON) electrolyte, which also acts as a separator. The lithium anode has a theoretical specific capacity of approximately 3800 mAh/g (as compared with the graphite anode used in lithium-ion and lithium polymer batteries, which has a theoretical specific capacity of only approximately 372 mAh/g), which allows for an increased energy density of solid-state batteries.
Because solid-state batteries use a solid-state electrolyte, rather than a liquid electrolyte, solid-state batteries do not present the safety issues that lithium-ion and lithium polymer batteries do. Additionally, solid-state batteries can have an energy density of approximately 1000 Wh/L.